1. Field of the Invention
The present invention relates to a stereoscopic image display apparatus, and in particular, to a stereoscopic image display apparatus suitable for performing stereoscopic display in a TV set, a VCR, a computer monitor, a game machine, and the like.
2. Description of Related Art
As a stereoscopic image display apparatus, there is, for example, a so-called multiple lens system proposed in the published European Patent Application No. 1 248 473 (A1).
This stereoscopic image display apparatus expresses stereoscopic effects by displaying original images of a certain observation object, corresponding to different observation positions, on an image display unit, and leading light from the image display unit so as to be able to observe these original images from the observation positions (viewpoints) respectively.
Nevertheless, this conventional stereoscopic image display apparatus has the following defects to be improved.    (1) Since it is necessary to use a transmissive display as an image display unit that displays the original images, degrees of freedom of display unit selection are lowered.
In addition, though LCDs are widely used now as transmissive display units, recent LCDs tend to largely scatter illumination light when the illumination light penetrates each of the LCDs because pixel structure is made fine so as to improve a viewing angle characteristic. Therefore, so as to use such an LCD for a multiviewpoint stereoscopic image display apparatus, it is necessary to specify a direction of display light so that the display light may reach only the observation positions, corresponding to the respective pixels, in a location where the display light from respective pixels is apart by desired observation distance.
At this point, the above-described conventional stereoscopic image display apparatus has the structure that gives directionality to the illumination light that illuminates pixels of the transmissive display unit. Nevertheless, there is a problem that, when the diffusion of the LCD increases, there arises a problem that, since the LCD scatters the illumination light even if the directionality is given to the illumination light, arrival positions of the illumination light in the observation plane shift, and hence, a stereoscopic image cannot be properly observed because so-called crosstalk arises.    (2) In the structure of the conventional stereoscopic image display apparatus, when performing color display, there is no position where it is possible to observe an image in colors since colors are separated on an observation plane by the color filter arrangement of the LCD.    (3) Moreover, in the stereoscopic image display apparatus proposed in the above-described publication, since components, proceeding in directions other than an observation position, in the illumination light from a pixel are interrupted by using a mask, a light efficiency is low.